* The names are slightly different: There might be a misspelling, or a similar-sounding name.
* The test is unpublished or limited access: Some tests are developed for specific research and not publicly available.
* The information is inaccurate: The source mentioning Cassel and Chow might be mistaken.
To find a relevant measure, you'd need to provide more context: Where did you encounter this information (book, article, website)? Knowing the context might help clarify what test is being referred to, or whether the information is correct. There are many different ways to measure cognitive dissonance, and perhaps a different scale or methodology is being described.